In what police called "a horrible, horrible" accident, Christa Engles from Tulsa, Oaklahoma was shot in the head after the toddler managed to get hold of a loaded semiautomatic handgun.

Christa's mother, who lived with Christa, her husband and the two children, came home to discover the horrific scene and the two children covered in blood.

Christa was rushed to hospital in a "grave condition". She was pronounced dead at 5:38 pm.

As the toddler was taken from the scene to be interviewed by police, he kept repeating, "Mommy shot, mommy shot," one report said.

A neighbour told reporters that the toddler found the gun under the couch.

According to Tulsa World, child specialists were called in to interview the little boy and “confirmed what the evidence led investigators to assume.”

“We think this is a horrible, horrible accident,” Sergeant Dave Walker said. “The neighbours, family, co-workers, and church family quickly gathered around this family in support of them during this terrible time."